Heavy oils or crude oils are occasionally discharged in sea water upon tanker accidents. Heavy oils or crude oils are mixtures of aromatic oils (aroma oils), nephthene oils, paraffin oils, etc. and contain a large amount of the aromatic oils. Because heavy oil or crude oil spills, which have a smaller specific gravity than sea water, initially afloat on a surface of the sea water in the form of lumps. Paraffin oils and naphthene oils having a low viscosity are gradually separated by diffusion from the lumps due to forces of waves or currents. The remaining aromatic oils having a high density sink in the sea. Thus, part of the oil spills deposits on the seashores and oil deposits are adhered to rocks. It is, therefore, difficult to remove the oil deposits.
In addition to a manual method in which oils are collected with an oil fence and manually recovered, processes are known for treating oil spills in which the oils are decomposed with crude oil decomposing bacteria or the oils are mixed with sea water using an emulsifier. The emulsifier and the crude oil decomposing bacteria used as a treatment agent for this purpose serve to convert the oil into fine particles which are easily mixed with the sea water by emulsion and dispersion and to accelerate the spontaneous purification (destroy of oils such as through decomposition by bacteria, and oxidation and vaporization by sunlight). However, such spontaneous purification proceeds so slowly that the known methods are not practical. Additionally, with this method, it is more and more difficult to recover the oil because, in an accident of discharge of a large amount of oil, the oil treating agent diffuses into and is diluted with a non-polluted region with time due to waves and currents. Thus, in practice, it is the general method to collect the discharged oil manually.
Tanker accident is not the sole cause of discharge of heavy oils or crude oils. Discard of waste oils from ships and discharge from oil tanks in harbors also cause such a problem. Similar to the removal of oil deposits on rocks, cleaning of oil deposits on tanks brings about a difficulty.
It is, therefore, an object of the present invention to provide a process which can easily recover oil spills. Another object of the present invention is to provide a process which can recover such oils while minimizing environmental pollution. It is a further object of the present invention to provide a process which can easily remove and recover oil deposits on solid surfaces.